1. Field of the Invention
The present invention relates to the correction of image artifacts in X-ray computed tomography that are caused by stray radiation.
2. Description of the Prior Art
Just like beam hardening effects scattering effects can cause undesired image artifacts in the reconstructed tomographic image of a transirradiated layer of a patient or some other object under examination. These image artifacts simulate structures corresponding to no real anatomy of the object under examination, and therefore lead to misinterpretations of the tomographic image. Particularly in the medical sector, such misinterpretations can have grave consequences to the extent of endangering the life of the patient.
In order to suppress the stray radiation component in the radiation intensity values measured with a detector, it is known to collimate at the detector side the X-ray radiation transirradiating the object under examination. As a rule, collimators are produced from tungsten, which is very well suited for this because of its high attenuation. However, tungsten has the disadvantage of being very expensive. This cost disadvantage is particularly significant when the detector is a detector matrix with a multiplicity of detector elements arranged next to one another in a number of superimposed detector rows. In the case of such detectors, the depth of the collimator shaft provided for each individual detector element must be enlarged with an increasing number of rows. The outlay for design and materials would be viewed as no longer acceptable starting from a certain number of detector rows.